1. Field of the Invention
The present invention relates to an information-communication terminal, particularly to an information-communication terminal which can reduce electric power consumption.
2. Description of the Background Art
Recently, a wireless communication in which a base station (access point) is not used becomes popular in a plurality of information-communication terminals. A network including only terminals which can conduct the wireless communication without the base station is called an ad hoc network.
There are disclosed various techniques relating to the terminal which can conduct communication in the ad hoc network. For example, Japanese Patent Laying-Open No. 2000-115012 discloses a portable communication device which can easily exchange data in the general public by making transition of an operation mode.
In the technique disclosed in Japanese Patent Laying-Open No. 2000-115012, basically each portable communication device repeatedly transmits a message of itself at intervals of five seconds in order that the general public can exchange the messages among one another. When an energy saving mode (operation mode having a long transmission interval) or a sleep mode (pause) is detected in repeating the message transmission, the operation mode is caused to make the transition to the energy saving mode or sleep mode. In the operation modes such as the energy saving mode and the sleep mode, the transmission interval is lengthened, one of the transmission and reception is stopped, a transmission radio wave is weakened, or the intermittent operation is performed. Because a condition that makes the transition to the energy saving mode or sleep mode depends on the presence or absence of the reception within a predetermined time, it is difficult to finely adjust electric power consumption.
In the wireless LAN (Local Area Network) ad hoc network, reduction of the electric power consumption is demanded because of the portable terminal. However, as described above, only the conventional terminal always waits for the reception, or the conventional terminal makes the transition to the sleep mode or energy saving mode when data cannot be received for a predetermined period. Therefore, there is no proposed a finer countermeasure for the reduction of the electric power consumption.